Introduce script to run from continuous integration
Get as many errors as possible

We should run as many other checks as possible even if tests fail.
Allow using, instead of cabal, another command (say cabal-dev)
Merge pull request #39 from Blaisorblade/issue/26

Fix #26 - introduce script to run from continuous integration
Switch to Doc to create usage message.
Mention supported instances in --help text (see #32).
Format --enumerate-instances output as a table (see #32).
Mention licensing for contributions in readme.
Add three-clause BSD license (see #29).
Remove test "same free variables" (fix #33).

This test made sense for alpha equivalence, but since
491eeb10f0597b19d7fa0280e17c75d5b414d238, we don't have
alpha-equivalence as a separate function. Instead, we use
alpha-beta-equivalence, which does not have the property
tested in this test.
Disable tests for transitivity and symmetry (fix #23).

The properties tested by these tests should be true, but our test
case generator often fails to produce appropriate terms for testing
them. This leads to spurious errors, because "cannot find any inputs"
is treated like "property failed" by our test framework.

After improving the test case generation (see #31), the tests could
be activated again.
Fix #29: Reenable cabal check
Merge pull request #43 from Blaisorblade/issue/29

Fix #29: Reenable cabal check